Evaluation of fumonisin contamination in cornflakes on the Belgian market by "flow-through" assay screening and LC-MS/MS analyses

A total of 205 cornflake samples collected in Belgian retail stores during 2003-2004 were surveyed for the natural occurrence of fumonisin B1 (FB1), B2 (FB2), and B3 (FB3). These cornflake samples, originating from conventional as well as from organic production, were analyzed using an intralaboratory-validated LC-MS/MS method. Additionally, 90 cornflake samples were subjected to rapid screening using a flow-through enzyme immunoassay method to demonstrate the practicability of a screening test coupled to a validated confirmatory LC-MS/MS method for the management of food safety risks. FB(1) concentrations ranged from not detected (nd) [LOD (FB1) = 20 microg/kg] to 464 microg/kg with mean and median concentrations of respectively 104 +/- 113 and 54 microg/kg. For FB2 and FB3, the concentration ranges varied respectively from nd [LOD (FB2) = 7.5 microg/kg] to 43 microg/kg and from nd [LOD (FB3) = 12.5 microg/kg] to 90 microg/kg. Mean concentrations for FB2 and FB3 were respectively 12 +/- 8 and 21 +/- 15 microg/kg, while the median concentration was 11 microg/kg for FB2 and 19 microg/kg for FB3. From the statistical tests (chi2 and ANOVA model III), it could be concluded that the agricultural practice did not have any significant effect on the fumonisin concentrations but that the variation between different batches was significant (p < 0.0001).     

Mycoflora and occurrence of aflatoxin B(1) and fumonisin B(1) during storage of Brazilian sorghum

The present study is a 1-year follow up of the mycoflora of 140 samples of Brazilian freshly harvested (10) and stored (130) sorghum, the levels of aflatoxin and fumonisin contamination detected in the grains, and the prevailing abiotic factors (grain moisture content, water activity, temperature, relative humidity, and mean rainfall) at the time of sampling. The results show a predominance of the genera Phoma (57.1%), Aspergillus (42.7%), Fusarium (25.0%), and Rhizopus (21.4%) and the presence of nine other filamentous fungi. Fusarium, Aspergillus, and Penicillium, the three most important genera in terms of toxicity, presented numbers of colony forming units per gram of sorghum (CFU/g) that varied from 1 x 10(3) to 36 x 10(3), from 1 x 10(3) to 295 x 10(3), and from 1 x 10(3) to 20 x 10(3) CFU/g, respectively. The species most frequently found were Aspergillus flavus and Fusarium moniliforme. Of the total samples analyzed, 12.8% were contaminated with aflatoxin B(1) (concentration mean = 7-33 microg/kg) and 74.2% with fumonisin B(1) (concentration mean = 0.11-0.15 microg/g). This paper is the first report of the natural occurrence of aflatoxins and fumonisins in sorghum grain from Brazil.     

Efficacy of a mycotoxin binder against dietary fumonisin, deoxynivalenol, and zearalenone in rats

It was hypothesized that a mycotoxin binder, Grainsure E, would inhibit adverse effects of a mixture of fumonisin B1, deoxynivalenol, and zearalenone in rats. For 14 and 28 days, 8-10 Sprague-Dawley rats were fed control diet, Grainsure E (0.5%), toxins (7 μg fumonisin B1/g, 8 μg of deoxynivalenol/g and 0.2 μg of zearalenone/g), toxins (12 μg of fumonisin B1/g, 9 μg of deoxynivalenol/g, and 0.2 μg of zearalenone/g + Grainsure E), or pair-fed to control for food intake of toxin-fed rats. After 28 days, decreased body weight gain was prevented by Grainsure E in toxin-fed female rats, indicating partial protection against deoxynivalenol and fumonisin B1. Two effects of fumonisin B1 were partly prevented by Grainsure E in toxin-fed rats, increased plasma alanine transaminase (ALT) and urinary sphinganine/sphingosine, but sphinganine/sphingosine increase was not prevented in females at the latter time point. Grainsure E prevented some effects of fumonisin B1 and deoxynivalenol in rats.     

Reduction of fumonisin B1 in corn grits by single-screw extrusion

This study was designed to determine the efficacy of extrusion in reducing fumonisin B1 in corn flaking grits in the presence and absence of glucose. In addition, degradation products of fumonisin B1 during extrusion were identified and quantitated with a mass balance approach. Uncontaminated clean corn grits, grits spiked with 30 microg/g fumonisin B1, and grits fermented with Fusarium verticillioides M-2552 (40-50 microg/g fumonisin B1) were extruded in the presence and absence of glucose (10%, w/w) using a single-screw extruder. Extrusion decreased fumonisin B1 by 21-37%, whereas the same process with added glucose further decreased fumonisin B1 by 77-87%. LC-fluorescence and LC-MS showed that most fumonisin in the extruded samples without added glucose was the fumonisin B1 form, whereas the main degradation product in grits extruded with glucose was N-(deoxy- d-fructos-1-yl)fumonisin B1. The formation of hydrolyzed fumonisin B1 was not significant during extrusion. Results suggest that extrusion in the presence of glucose may reduce fumonisin B1 in corn grits significantly.     

Occurrence of fumonisins B(2) and B(4) in retail raisins

Concerns that raisins may be contaminated by fumonisins stem from the persistent occurrence of Aspergillus niger spores on raisins and the recent discovery of fumonisin production by A. niger on grapes, which leads to the widespread occurrence of fumonisin B(2) in wine. This study presents an LC-MS/MS survey of fumonisins in retail raisins. In 10 of 21 brands collected in Denmark, Germany, and The Netherlands, fumonisins B(2) and B(4) were detected at levels up to 13 and 1.3 μg/kg, respectively. Only fumonisin B(2) has been detected in wine, so the presence of fumonisin B(4) in raisins suggests that the fumonisins are produced mainly during the drying process concomitant with the decreasing water activity. Analysis of multiple packages from one manufacturer showed a 3-fold package-to-package variation, suggesting that a few raisins per package are contaminated.     

Mycotoxin contamination of dietary and medicinal wild plants in the Eastern Cape Province of South Africa

Nineteen dietary and 30 medicinal wild plants used by residents of the Eastern Cape Province of South Africa were investigated for the presence of fumonisin B1 and aflatoxin B1. The plants were extracted in water, and cleanup was undertaken on immunoaffinity cartridges; analysis was by HPLC using fluorescence detection. None of the plant extracts contained detectable levels of aflatoxin B1; however, eight plants, four dietary and four medicinal, were positive for fumonisin B1 at levels ranging from 34 to 524 microg/kg and from 8 to 1553 microg/kg, respectively. The presence of fumonisin B1 was confirmed by LC-MS/MS using positive ion electrospray ionization. Fumonisin B1 provided characteristic fragment ions at m/z 704, 686, 546, 528, 370, and 352 corresponding to sequential loss of H2O and tricarboxylic acid moieties from the alkyl backbone. These results indicate that exposure to fumonisin B1 is much more widespread than initially thought and is the first report of mycotoxin contamination in South African medicinal and dietary wild plants.     

Liquid chromatographic determination of fumonisins B1, B2, and B3 in corn silage

Corn silage was dried, ground, and then extracted with 0.1 M ethylenediaminetetraacetic acid. The filtrate was applied to a FumoniTest immunoaffinity column. Fumonisins were derivatized with naphthalene-2,3-dicarboxaldehyde, separated on a C(18) liquid chromatographic column, and detected by fluorescence. The detection limits for fumonisin B(1), fumonisin B(2), and fumonisin B(3) were 50, 25, and 25 ng/g of dried silage, respectively. Recoveries of fumonisin B(1), fumonisin B(2), and fumonisin B(3) from wet and dried corn silage spiked over the range of 100-5000 ng/g averaged 91-106%. The method was applied to corn silage samples collected from the midwestern area of the United States during 2001-2002. Of 89 corn silage samples, fumonisin B(1), fumonisin B(2), and fumonisin B(3) were found in 86 (97%), 64 (72%), and 51 (57%) of the samples. The mean positive levels of fumonisin B(1), fumonisin B(2), and fumonisin B(3) were 615, 93, and 51 ng/g, respectively, in dried silage. This suggests that fumonisins may be frequent low level contaminants in corn silage.     

Characterization of fumonisin B(1)-glucose reaction kinetics and products

The reaction of fumonisin B(1) with the reducing sugar D-glucose can block the primary amine group of fumonisin B(1) and may detoxify this mycotoxin. A method to separate hundred milligram quantities of fumonisin B(1)-glucose reaction products from the excess D-glucose with a reversed-phase C(18) cartridge was developed. Mass spectrometry revealed that there were four primary products in this chain reaction when fumonisin B(1) was heated with D-glucose at 65 degrees C for 48 h: N-methyl-fumonisin B(1), N-carboxymethyl-fumonisin B(1), N-(3-hydroxyacetonyl)-fumonisin B(1), and N-(2-hydroxy, 2-carboxyethyl)-fumonisin B(1). The N-(1-deoxy-D-fructos-1-yl) fumonisin B(1) (fumonisin B(1)-glucose Schiff's base) was detected by mass spectrometry when fumonisin B(1) was heated with D-glucose at 60 degrees C. The nonenzymatic browning reaction of fumonisin B(1) with excess D-glucose followed apparent first-order kinetics. The activation energy, E(a), was 105.7 kJ/mol. Fumonisin B(1) in contaminated corn could precipitate the nonenzymatic browning reaction with 0.1 M D-glucose at 60 and 80 degrees C.     

N-(1-deoxy-D-fructos-1-yl) fumonisin B(1), the initial reaction product of fumonisin B(1) and D-glucose

Incubation of fumonisin B(1) and D-glucose in aqueous solutions resulted in the formation of N-(1-deoxy-D-fructos-1-yl) fumonisin B(1) in addition to the previously reported N-(carboxymethyl) fumonisin B(1). N-(1-Deoxy-D-fructos-1-yl) fumonisin B(1) is the first stable product formed after the Amadori rearrangement of the Schiff base formed by the reaction of the primary amine of fumonisin B(1) and the aldehyde group of D-glucose. N-(1-Deoxy-D-fructos-1-yl) fumonisin B(1) was synthesized by reacting fumonisin B(1) with an excess of D-glucose in methanol and heating for 6 h at 64 degrees C. It was purified using C(18) and strong cation exchange solid-phase extraction cartridges and characterized by nuclear magnetic resonance and liquid chromatography-mass spectrometry. Subsequently, N,N-dimethylformamide was found to be a better reaction solvent, requiring reaction for only 2-3 h at 64 degrees C and eliminating the formation of methyl esters. Alkaline hydrolysis of N-(1-deoxy-D-fructos-1-yl) fumonisin B(1) gave a mixture of hydrolyzed fumonisin B(1) and hydrolyzed N-(carboxymethyl) fumonisin B(1).     

Determination of N-(carboxymethyl)fumonisin B(1) in corn products by liquid chromatography/electrospray ionization--mass spectrometry

It is well-known that fumonisin B(1) (FB(1)) in corn meal decreases during baking, frying, and cooking, but it is still not exactly clear how heating affects the formation of N-(carboxymethyl)fumonisin B(1) (NCM-FB(1)), the reaction product of FB(1) and reducing sugars. In model experiments corn grits were spiked with FB(1) (2 mg/kg) and D-glucose (50 g/kg) or sucrose (50 g/kg) and manufactured into extrusion products at various temperatures (160--180 degrees C) and moisture levels (16--20%). A liquid chromatography/electrospray ionization-mass spectrometry method using isotopically labeled fumonisin FB(1)-d(6) as an internal standard was developed for the determination of NCM-FB(1). For sample cleanup solid-phase C18 cartridges were used. The detection limit achieved with this method was 10 ng/g (signal-noise ratio = 3:1) using the protonated molecule [M + H](+) signal of NCM-FB(1) (m/z 780) in the selected ion monitoring mode. Low concentrations of NCM-FB(1) (29-97 ng/g) were detected in all samples spiked with D-glucose and FB(1), whereas those spiked with FB(1) and sucrose showed only NCM-FB(1) in samples produced at 180 degrees C (NCM-FB(1) = 27 ng/g). Various corn-containing food samples from the German market were analyzed for the presence of NCM-FB(1), FB(1), and hydrolyzed fumonisin B(1) (HFB(1)). All samples were contaminated with FB(1) (22--194 ng/g) and HFB(1) (5--247 ng/g). Six of nine samples contained NCM-FB(1) in low concentrations ranging from 10 to 76 ng/g. From these data and the low toxicity of NCM-FB(1) it can be concluded that the significance of NCM-FB(1) in food seems to be a minor one.     

Analysis of acrylamide,a carcinogen formed in heated foodstuffs

Reaction products (adducts) of acrylamide with N termini of hemoglobin (Hb) are regularly observed in persons without known exposure. The average Hb adduct level measured in Swedish adults is preliminarily estimated to correspond to a daily intake approaching 100 microg of acrylamide. Because this uptake rate could be associated with a considerable cancer risk, it was considered important to identify its origin. It was hypothesized that acrylamide was formed at elevated temperatures in cooking, which was indicated in earlier studies of rats fed fried animal feed. This paper reports the analysis of acrylamide formed during heating of different human foodstuffs. Acrylamide levels in foodstuffs were analyzed by an improved gas chromatographic-mass spectrometric (GC-MS) method after bromination of acrylamide and by a new method for measurement of the underivatized acrylamide by liquid chromatography-mass spectrometry (LC-MS), using the MS/MS mode. For both methods the reproducibility, given as coefficient of variation, was approximately 5%, and the recovery close to 100%. For the GC-MS method the achieved detection level of acrylamide was 5 microg/kg and for the LC-MS/MS method, 10 microg/kg. The analytic values obtained with the LC-MS/MS method were 0.99 (0.95-1.04; 95% confidence interval) of the GC-MS values. The LC-MS/MS method is simpler and preferable for most routine analyses. Taken together, the various analytic data should be considered as proof of the identity of acrylamide. Studies with laboratory-heated foods revealed a temperature dependence of acrylamide formation. Moderate levels of acrylamide (5-50 microg/kg) were measured in heated protein-rich foods and higher contents (150-4000 microg/kg) in carbohydrate-rich foods, such as potato, beetroot, and also certain heated commercial potato products and crispbread. Acrylamide could not be detected in unheated control or boiled foods (<5 microg/kg). Consumption habits indicate that the acrylamide levels in the studied heated foods could lead to a daily intake of a few tens of micrograms.     

Comparison of extraction buffers for the detection of fumonisin B(1) in corn by immunoassay and high-performance liquid chromatography

The Associatian of Official Analytical Chemists approved method for quantification of fumonisin B(1) (FB(1)) in corn meal or corn-based food products includes extraction into methanol (MeOH)/water (3:1, v/v). Disposal of the extraction medium can pose safety and environmental problems. To secure a rapid and inexpensive screen for FB(1) contamination, a sensitive competitive ELISA using a rabbit polyclonal antibody was developed. This assay was used in a comparative study measuring the extraction efficiency of FB(1) in aqueous or organic solvent buffers using 16 field corn samples. An aqueous phosphate buffer was found to be suitable for extracting FB(1), thus eliminating the need for organic solvents. HPLC and ELISA determinations compared well in fortified samples at known concentrations between 1 and 50 microg/mL of extract. Overestimation at levels >50 microg/mL were common. The characteristics and application of the ELISA for screening purposes are discussed.     

Incidence of Fusarium verticillioides and levels of fumonisins in corn from main production areas in Iran

A total of 52 corn samples collected in 2000 from four main corn production provinces of Iran (Fars, Kermanshah, Khuzestan, and Mazandaran) were analyzed for contamination with Fusarium verticillioides and fumonisins (FB(1), FB(2), FB(3), and 3-epi-FB(3)). The mean incidence of F. verticillioides (percent of kernels infected) for these four areas was 26.7, 21.4, 24.9, and 59.0%, respectively. The incidence in Mazandaran was significantly (p < 0.05) above that of the other areas. All samples from Mazandaran were contaminated with fumonisins with a mean level of total fumonisins of 10674 microg/kg. In contrast, the incidence of fumonisin contamination above 10 microg/kg was 53 (8/15), 42 (5/12), and 57% (8/14) in the samples from Fars, Kermanshah, and Khuzestan, respectively, and the corresponding mean total fumonisin levels were 215, 71, and 174 microg/kg, respectively. No statistical differences (p > 0.05) were observed in the fumonisin levels of the corn samples from these three provinces, which were significantly (p < 0.05) lower than the fumonisin contamination in samples from Mazandaran.     

Natural occurrence of fumonisins B(1) and B(2) in domestic maize of Taiwan.

Samples of maize grown in various districts of Taiwan were collected and analyzed for the presence of fumonisin B(1) (FB(1)) and fumonisin B(2) (FB(2)) using high-performance liquid chromatography. Forty-nine (44.5%) and 2 (1.8%) of 110 samples were found to contain FB(1) (109-1148 ng/g) and FB(2) (222-255 ng/g), respectively. The frequency of detection and also the maximum FB(1) concentration were found in samples from Penton (2/2, 262 ng/g), followed by Chiayi (18/26, 264 ng/g), Tainan (8/16, 160 ng/g), Hualinen (5/14, 1148 ng/g), Taitung (7/20, 109 ng/g), and Yunlin (9/26, 361 ng/g). Of the 110 samples examined, only 2 samples from Hualinen had been detected containing FB(2). During an analysis of the distribution pattern of FB(1), it became apparent that >79% of tested samples had FB(1) concentrations <100 ng/g, whereas 2.7% (or 3 samples) contained FB(1) >300 ng/g. These results clearly illustrated that domestically produced maize for human consumption is frequently contaminated with FB(1).     

Mycoflora and fumonisin mycotoxins associated with cowpea [Vigna unguiculata (L.) Walp] seeds

Cowpea seed samples from South Africa and Benin were analyzed for seed mycoflora. Fusariumspecies detected were F. equiseti, F. chlamydosporum, F. graminearum, F. proliferatum, F. sambucinum, F. semitectum, and F. subglutinans. Cowpea seed from South Africa and Benin and F. proliferatum isolates from Benin, inoculated onto maize patty medium, were analyzed for fumonisin production. Samples were extracted with methanol/water and cleaned up on strong anion exchange solid phase extraction cartridges. HPLC with precolumn derivatization using o-phthaldialdehyde was used for the detection and quantification of fumonisins. Cowpea cultivars from South Africa showed the presence of fumonisin B(1) at concentrations ranging between 0.12 and 0.61 microg/g, whereas those from Benin showed no fumonisins. This is believed to be the first report of the natural occurrence of FB(1) on cowpea seed. Fumonisin B(1), B(2), and B(3) were produced by all F. proliferatum isolates. Total fumonisin concentrations were between 0.8 and 25.30 microg/g, and the highest level of FB(1) detected was 16.86 microg/g.     

Simultaneous determination of fumonisin B(1) and hydrolyzed fumonisin B(1) in corn products by liquid chromatography/electrospray ionization mass spectrometry

A method for the simultaneous determination of fumonisin B(1) (FB(1)) and its major hydrolysis product (HFB(1)), which is known to be formed during alkaline treatment of fumonisin-containing corn meal, was devised to analyze the levels of these mycotoxins in corn products available on the German market. Liquid chromatography/electrospray mass spectrometry in combination with selected ion monitoring (SIM) was used for unambiguous detection of FB(1) and HFB(1) after extraction of samples with acetonitrile/methanol/water (25:25:50) and solid-phase C18 cleanup. Quantitation was carried out using labeled fumonisin FB(1)-D(6) as an internal standard. The detection limits achieved with this method were 8 ng/g for HFB(1) (signal-noise ratio = 5:1) and 5 ng/g for FB(1) (s/n = 5:1) using the protonated molecule signals m/z 406 and 722 in the SIM mode. A screening of several corn-containing foodstuffs, among them extrusion products and alkali-processed corn food such as tortilla chips, showed HFB(1) and FB(1) contamination with levels of 8-80 and 5-450 ng/g, respectively.     

Structure and natural occurrence of stereoisomers of the fumonisin B series mycotoxins

1H and 13C NMR spectroscopy of both fumonisin B3 and B4, as well as high-performance liquid chromatography (HPLC) analysis of samples of fumonisin B3 used as standards, showed in each case the presence of two stereoisomers, which could not be separated by preparative chromatography. The 2,3-anti relative configuration for the two minor stereoisomers of fumonisin B3 and B4 was deduced from the NMR data, and their 2S,3R absolute configurations were established by application of Mosher's method using the fumonisin B3 sample. Samples of fumonisin B3 and B4 can contain between 10 and 40% of fumonisin B compounds of the 3-epi series. The 3-epi-FB3, determined by HPLC with fluorescence detection of the o-phthaldialdehyde derivative and confirmed by liquid chromatography-tandem mass spectrometry, was found to occur naturally in a range of maize samples at levels much lower than FB3 (< 20%). The identification of members of the 3-epi-fumonisin B series provides insight into the order and selectivity of steps in fumonisin biosynthesis.     

Natural occurrence of fumonisins in corn from Iran

Corn collected in the Mazandaran and Isfahan Provinces of Iran was analyzed for fumonisin B(1) (FB(1)), fumonisin B(2) (FB(2)), and fumonisin B(3) (FB(3)). The samples from Mazandaran Province, situated on the Caspian littoral of Iran, were random samples from farmers' corn lots collected in September 1998, whereas those from Isfahan Province, situated further south in the center of Iran, were bought as corn cobs in the local retail market during October 1998. All 11 samples from Mazandaran showed high levels of fumonisin contamination with FB(1) levels between 1.270 and 3.980 microg/g, FB(2) levels between 0.190 and 1.175 microg/g, and FB(3) levels between 0.155 and 0.960 microg/g. Samples from Isfahan showed lower levels of contamination with eight of eight samples having detectable FB(1) (0.010-0.590 microg/g), two of eight samples having detectable FB(2) (0.050-0.075 microg/g), and two of eight samples having detectable FB(3) (0.050-0.075 microg/g). This is the first report of fumonisin contamination of corn from Iran, in which samples from the area of high esophageal cancer on the Caspian littoral have been shown to contain high levels of fumonisins.     

Survey of mycotoxins in U.S. distiller's dried grains with solubles from 2009 to 2011

Distiller's dried grains with solubles (DDGS) is a major coproduct of the fuel-ethanol industry and is becoming a popular low-cost ingredient for animal feed. Uncertainties regarding the risk factors in DDGS, such as level of mycotoxins, could limit its application in the animal feed industry. To provide a scientifically sound assessment of the prevalence and levels of mycotoxins in U.S. DDGS, we measured aflatoxins, deoxynivalenol, fumonisins, T-2 toxin, and zearalenone in 67 DDGS samples collected from 8 ethanol plants in the midwestern United States from 2009 to 2011. Among the five mycotoxins, deoxynivalenol was the main focus of the study because the crop year of 2009 was favorable for deoxynivalenol occurrence in corn. We learned that no more than 12% of the samples contained deoxynivalenol levels higher than the minimum advisory level for use in animal feed provided by the U.S. FDA, and the deoxynivalenol levels in all DDGS collected in 2011 were <2 mg/kg. Besides, intensive study showed that the enrichment of deoxynivalenol from contaminated corn to DDGS was about 3.5 times. With regard to the other mycotoxins in DDGS, the study suggested that (1) almost none of the DDGS samples produced in 2010 contained detectable aflatoxins and the highest level of aflatoxins in DDGS was 5.7 μg/kg; (2) no more than 6% of the samples contained fumonisin levels higher than the guidance level for feeding equids and rabbits provided by the U.S. FDA; (3) none of the samples contained T-2 higher than the detection limit; (4) most samples contained zearalenone levels between 100 and 300 μg/kg. This study was based on representative DDGS samples from the U.S. ethanol industry, and the data were collected using state-of-the-art analytical methodology. This study provided a comprehensive and scientifically sound assessment of the occurrence and levels of mycotoxins in DDGS produced from 2009 to early 2011 by the U.S. ethanol industry.     

Aflatoxin and fumonisin contamination of commercial corn (Zea mays) hybrids in Mississippi

Resistance to mycotoxin contamination was compared in field samples harvested from 45 commercial corn (maize) hybrids and 5 single-cross aflatoxin-resistant germplasm lines in years with high and moderate heat stress. In high heat stress, mycotoxin levels were (4.34 +/- 0.32) x 10(3) microg/kg [(0.95-10.5 x 10(3) microg/kg] aflatoxins and 11.2 +/- 1.2 mg/kg (0-35 mg/kg) fumonisins in commercial hybrids and 370 +/- 88 microg/kg (140-609 microg/kg) aflatoxins and 4.0 +/- 1.3 mg/kg (1.7-7.8 mg/kg) fumonisins in aflatoxin-resistant germplasm lines. Deoxynivalenol was detected (one-fourth of the samples, 0-1.5 mg/kg), but not zearalenone. In moderate heat stress, mycotoxin levels were 6.2 +/- 1.6 microg/kg (0-30.4 microg/kg) aflatoxins and 2.5 +/- 0.2 mg/kg (0.5-4.8 mg/kg) fumonisins in commercial hybrids and 1.6 +/- 0.7 microg/kg (0-7 microg/kg) aflatoxins and 1.2 +/- 0.2 mg/kg (0.5-3.0 mg/kg) fumonisins in aflatoxin-resistant germplasm lines. The results are consistent with heat stress playing an important role in the susceptibility of corn to both aflatoxin and fumonisin contamination, with significant reductions of both aflatoxins and fumonisins in aflatoxin-resistant germplasm lines.